Electrochemical cells, such as fuel cells, may utilize hydrogen and oxygen as reactants to generate electricity in an electrochemical reaction. While oxygen may be obtained directly from the ambient atmosphere, hydrogen may be provided to the electrochemical cells from a supply system configured to store the hydrogen, and to deliver the hydrogen to the electrochemical cells when required. Accordingly, when the hydrogen in the supply system is depleted, replenishment of the hydrogen may be necessary before further electrical generation may occur.